Patent attributes
An approach for incrementally updating graphical images when using anti-aliasing techniques is disclosed. Data for an original color is stored, and an image is filtered based on the original color. A new color for an image portion less than the entire image is identified. The new color is used with the old color to re-filter the image portion. The re-filtering may be performed by a two-step approach in which the image portion is filtered using the negative of the original color and then the image portion is filtered using the new color. The re-filtering may be performed by a one-step approach in which the portion of the image is filtered using the difference between the new color and the old color. The appearance of a halo around the portion of the image that would otherwise occur when filtering based on only the new color is thereby avoided.
